The invention relates to a method of separating flat, stacked products according to the preamble of claim 1 and to a separating apparatus for separating flat products according to the preamble of claim 2.
A method and a separating apparatus of the type mentioned here are known. In order to process flat products further, for example sheet-metal panels, sheets of paper or board, these are provided stacked on one another. In order to feed them to a further processing apparatus, for example a printing machine, the flat products are picked up individually from the stack. For this purpose, it is known to arrange a stack of products under a feeder with a separating apparatus. The separating apparatus comprises a pick-up device having a lifting element for the product resting at the top of the stack. Using the lifting element, the respective uppermost product is lifted, so that said product can be transferred to a transport device, which leads the product to the further processing apparatus arranged downstream of the separating apparatus. Depending on the number of products picked up from the stack, the remaining stack of products is moved up with the aid of a lifting device, so that the respective uppermost product is located in the access range of the lifting element. The drawback with the known method and the apparatus is that lifting the uppermost product off the stack of products can take place only when the previous product has been removed from the stack of products, with the aid of the transport device, to such an extent that its trailing edge region no longer overlaps the stack of products. As a result, only a correspondingly low number of products per unit time can be separated and fed to the further processing apparatus.
It is therefore the object of the invention to specify a method of separating flat, stacked products with which a large number of products per unit time can be lifted off the stack of products and fed to a further processing process. A further objective of the invention is to provide an apparatus for implementing the method which preferably has a simple construction.
In order to achieve this object, a method of separating flat, stacked products is proposed which has the features cited above. In order to process the flat products further, in particular sheet-metal panels, sheets of paper or board, these are picked up individually one after another from the stack of products and fed individually to a further processing process. After the uppermost product has been lifted off the stack of products, it is transported away in the transport direction to the further processing process. In this case, provision is made for the transport direction to be inclined with respect to the vertical axis of the stack of products by an anglexe2x88x9d which preferably lies in the range from 30xc2x0 to 150xc2x0. The xe2x80x9cvertical axisxe2x80x9d of the stack of products is understood to mean that axis which extends orthogonally to the base area of the stacked products. The method is distinguished by the fact that as the product that still partially overlaps the stack with its trailing edge region is transported away, a following product is already being lifted off the stack of products, in its trailing edge region, to be transported away. This is possible since a lifting action which is partially carried out is carried out outside the region of overlap with the preceding product, and because of its elasticity the product permits a preferably S-shaped bend, so that the leading edge region of the product which is located in the overlap region still rests on the stack while the trailing edge region is already being lifted. If the product has a high stiffness, it will bend only little elastically, that is to say as it is lifted it passes through a number of tilting movements. In conjunction with the present invention, the term xe2x80x9coverlapxe2x80x9d is understood to mean thatxe2x80x94as viewed transversely with respect to the transport direction of the productxe2x80x94the trailing edge region of the previous product is still located above the stack of products while the following product is already being lifted off the stack of products. Viewed in plan view, therefore, the previous product, being transported away, still partially covers the stack of products during the action of partially lifting the following product. By this means, by comparison with the method known from the prior art, more products per unit time can be processed, so that the utilization of a subsequent further processing process can be optimized.
In order to achieve the object, an apparatus for separating flat, stacked products having the features cited above is also proposed. The apparatus comprises a pick-up device and a transport device, which are used to lift the uppermost product off the stack of products and to transport the separated products away. The products are preferably fed to a further processing apparatus. In connection with the present invention, the term xe2x80x9cfurther processing apparatusxe2x80x9d is also understood to mean a product transport device or separating apparatus or the like for the products. The transport direction, in which the goods are transported away, forms with the vertical axis of the stack of products an anglexe2x88x9dwhich preferably lies in the range from 30xc2x0 to 150xc2x0. The apparatus is distinguished by the fact that the transport device has at least two overhead transporting means whichxe2x80x94as viewed in the transport directionxe2x80x94are arranged one behind another and in each case above the stack of products and in each case in a position overlapping the stack of products. On the basis of this configuration, it is possible that while a product already lifted off the stack of products is being transported away and, at the same time, its trailing edge region still overlaps the stack of products, the following product, located at the top of the stack of products, is already being partially lifted off the stack of products. As a result, more producers can be separated per unit time than in the case of the separating apparatus known from the prior art, as a result of which the utilization of a further processing apparatus connected downstream of the separating apparatus can be optimized.
In a preferred embodiment of the separating apparatus, provision is made for the transporting means to be constructed as overhead suction belt sections. In each case, these comprise at least one endless belt, referred to as a run, which is led over rollers, rolls or other guide devices, it being possible for at least one of the rollers/rolls to be driven to rotate and preferably to be braked. The endless belt is provided with a number of passage openings and, on its side facing away from the product, can have a vacuum applied to it, which makes it possible to pick up the product by suction and hold it on the endless belt. The vacuum serving to achieve an adhesive action (suction action) is preferably adjustable or can be switched (on/off switching). The construction and the functioning of an overhead suction belt section are known, so that they do not need to be discussed specifically here.
In another design variant, provision is made for the overhead suction belt section to have a number of narrow belts, arranged at a distance from one another and transversely with respect to the transport direction of the product, in particular endless belts, whose respective width is less than that of the product.
In another exemplary embodiment of the separating apparatus, provision is made for the transporting means to be constructed as overhead magnetic sections, which can be employed in the case of products consisting of ferromagnetic material. Each of the overhead magnetic sections comprises at least one endless belt/belt run led over rollers, rolls or other guide devices, as well as at least one electromagnet, which can preferably be switched on and off, and/or at least one permanent magnet. The magnet can be arranged to be fixed in position with respect to the run, which can be driven and preferably also braked, on the side facing away from the product to be transported. Of course, it is also possible for the at least one magnet to be fitted to the endless belt on the side thereof facing toward or facing away from the product. In addition, in the case of the transporting means constructed as overhead magnetic sections, these can in each case comprise a number of endless belts arranged beside one another at a distancexe2x80x94as viewed in the transport direction of the productxe2x80x94which are provided or interact in each case with at least one electromagnet or permanent magnet. In a different design variant of the overhead magnetic sections, these each comprise a linear motor, whose construction and functioning are known per se. The product to be transported and consisting of ferromagnetic material, which is displaced in translator fashion, in this case forms the moving part (xe2x80x9crotorxe2x80x9d) of the linear motor, which is displaced with respect to the stationary part (xe2x80x9cstatorxe2x80x9d) of the linear motor.
In a preferred embodiment, provision is made for the pick-up device to have a number of pick-up means. These are arranged transversely with respect to the transport direction of the product, preferably beside one another and distributed at a distance from one another, preferably in the trailing edge region of the products lying on the stack. In a first design variant, a pick-up means is formed by at least one lifting sucker. The latter comprises, for example, a piston/cylinder unit, to whose moving part (piston rod or cylinder) there is fitted a suction head to which vacuum can be applied and which, by moving the moving part, can be displaced in the direction of the uppermost product lying on the stack and in the opposite direction. The suction head is constructed in such a way that the product can be picked up by suction and held, so that the product can be lifted off the stack by means of a displacement of the moving part of the cylinder/piston unit. In another design variant, the pick-up means is formed by at least one lifting magnet, which can be employed to separate products consisting of ferromagnetic material. The lifting magnet comprises, for example, a piston/cylinder unit, to whose moving part (piston rotor cylinder) at least one permanent magnet and/or an electromagnet which can be switched on and off is fixed. Of course, it is possible that, in the case of products consisting of ferromagnetic material, the pick-up device can comprise pick-up means formed both by lifting suckers and by lifting magnets.
Furthermore, an exemplary embodiment of the separating apparatus is preferred in which at least one of the transporting means at the same time executes the function of the pick-up device or one of the pick-up means. The transporting means is therefore constructed in such a way that it performs the action of lifting the uppermost product off the stack of products and also the action of transporting it away. In addition or else alternatively, it is possible for the action of lifting the uppermost product off the stack of products, initiated by a pick-up device, to be assisted by the transporting means.
In a particularly preferred embodiment, provision is made for the transporting means, arranged behind one another in the transport direction, to have drives that operate independently of one another. This is because it is possible that, for example, a first transporting means is in the rest position, that is to say at a standstill, when the uppermost product is being lifted partially off the stack of products, while the second transporting means, whichxe2x80x94as viewed in the transport directionxe2x80x94is arranged downstream of the first transporting means, is transporting a product already lifted completely off the stack in the direction of the further processing apparatus. It is preferable if the transport speed of the product to be transported can be adjusted or controlled with the aid of a control or regulating system for the drives.
In addition, an exemplary embodiment of the separating apparatus is preferred if it is distinguished by the fact that the overhead holding functions of the transporting means located in a position overlapping the stack of products can be activated or deactivated independently of one another. The overhead holding function is implemented, for example, with the aid of a vacuum and/or magnetic action in each case. On the basis of this configuration, it is possible for a product lifted off the stack of products to be displaced in the transport direction only by one of the two transporting means and held in the process, while the other transporting means, which the product has already left, is located in a passive functional position, that is to say in particular has been braked down to a standstill, in order to be able to accept the following product.
Finally, an exemplary embodiment of the separating apparatus is also preferred in whichxe2x80x94as viewed in the transport directionxe2x80x94an overhead outlet section, which is located in a position at least partially overlapping the stack of products, is connected downstream of the transport device. The overhead outlet section arranged above the stack of products can be constructed, for example, as a suction belt section or as a magnetic section and can comprise rolls/rollers, for example suction rolls/suction rollers, and/or otherxe2x80x94for example stationaryxe2x80x94guide devices, as well as an endless belt led over the rolls/rollers/guide devices. The product to be transported can therefore be held on the devices of the overhead outlet section by a suction action and/or by magnetic action. In one design variant, at least some of the rolls/rollers are provided with a drive, which permits the rolls/rollers to be driven and braked. In addition, it is possible for the overhead outlet section to have only freely rotating, non-driven rolls,rollers, transport belts or the like with a suction or magnetic device.
The non-driven outlet section makes it possible to stop the adjacent transporting means early. In addition or alternatively, because of such an outlet section, the result is the optionxe2x80x94as viewed in the transport directionxe2x80x94of operating an adjoining discharge transport section (reference symbol 53 or 49 in FIG. 2) at a constant, full speed, while the product is accelerated by the transporting means (singular or plural). When the product then passes to the discharge transport section, it has reached full speed, that is to say a jolt-free transfer takes place. The outlet section thus acts as a bridging section for the acceleration of the product.
Further advantageous embodiments of the separating apparatus emerge from the remaining subclaims.